Altec 290 series drivers

[Q-Man]

Originally posted by Rocktets:
I just looked at the spec on the Altec 290. Good up to 7Khz. Looks like the 2405 won't do, and will have to stick w/ the 2404H.

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[Q-Man]

Sorry for the last post, I'm new here and am trying to figure out this board.

I've been trying different Altec drivers and horns
with the Klipschorn bass horn. I've been trying to get this right for over a year now. I first tried the 288-16K drivers with the 805B horns. I prefered the sound over the stock Klipsch K-55 driver and K-400 midrange horn, but this combo was too weak from 400 to 500 Hz. The Klipsch bass horn drops off fast above 350 Hz. I've recently been playing with some 290-16K and L drivers with the 311-90 horns. This combo is much better, but still a little weak at 400 Hz. I like the improvement and it's a keeper. I'm crossing the 290 over to a JBL 2404H tweeter at 6000 Hz. I just sent a 290 driver and 311-90 horn to a friend of mind who has the proper test equipment to help tweak the network for me. He is telling me that the 290 has a Fs of 670 Hz. This isn't good. This means that the 290 is about 12dB down at 300 Hz. It might not be a good driver to crossover that low. I hope we can make it work, because I jumped the gun and bought six of the drivers and four horns over the last six months to use in my home theater. I'm still in the market for two more horns.

When I find out more about the 290 I'll let you know if you like.

I will post some pictures of the horn and driver tops for the Klipschorn if someone can tell me how to do it. I'm not very good on this computer.

[Todd W. White]

Something's wrong with that 290 - the mechanical resonance of that driver is around 225 Hz, and a properly operating 290 goes down to 300 Hz EASILY!

By the way - the 288 isn't really designed to go below 500 Hz...I would suspect the crossover you're using too, seeing as how two very different drivers exhibited the same problem on your system...

[Q-Man]

Thanks for the reply Todd.

I know the 288 and the 805 B isn't the combo for my needs. I tried it because some people I know are using it with their Klipschorns. So I tried it and learned the hard way.

As I said, I now have six 290 drivers and they all measure about the same with warble test tones using a sound level meter. I even bought 3 new diaphragms from Bill at Great Plains Audio to see if that would make a difference. They didn't. The problem may be the network. This friend of mine has had the driver for a week now and just received the horn today. He wants to check the impeadance of the driver on the horn. Then he plans on tweaking the network. The network is a Klipsch design using better parts. I measure the 290 about 2 to 3 dB down at the 400 Hz crossover point using the warble test tones. I hope the network is the answer. If not I guess I'll send Bill one of the drivers, and let him test it. I'll keep you posted on the results and please feel free to suggest anything.

The 290 and 311 have it all over Stock klipsch top end.

[Roland N R]

Hello Q:

Most people using 290s in 300 cycle horns/XO have trouble reaching past 4K Hz w/o resistor padding the mids and or EQ boosting the highs. Just curious...how high was your 290 in 311 horn with 300 Hz XO responding to +/- dB?? Resistor padding mids when crossed at 600 Hz has given flat response to 6.3K (+/- 1.5dB). Let me know what you find. By the way good to see a REAL HT nut!!

Roland

[Rockets]

Q-MAN, 'YOU' are the reason I started this thread over here! I've been following your project and it got me hooked of sorts. I posted here because I needed more info on the 290's before I start throwing money around and ended up with the wrong version(s). It still might be all for naught, and I'll find myself with a set of JBL 2123's (like JW) before it's over.

Having said that, I'm really curious as to the difference between using the stock Atlas/Klipsch driver w/ the 311 horn and using the Altec 290. Is it the dynamic range? The clarity? The separation? All the above, or none of the above ! LOL! I mean is the difference 'that' great like night and day?

Thanks! Appreciate the help.

[Q-Man]

Hello Roland,

I know that warble test tones and a sound level meter aren't the most accurate way to measure frequency response, but that's all I have to work with. Using this method I find the 290 is still flat to 6000 Hz. I actually have about a 2 dB peak at 6000 Hz, but I don't know if that is the 290 or the tweeter. I hate to keep mentioning this friend of mine, but he also thinks it will be better to crossover around 4000 Hz to the 2404H tweeter. Time will tell, this project is now in his hands with all his test equipment. I may be able to build the bass horns and the cabinets, but I need his help for the networks and the more technical stuff. That is one reason why I joined this board, maybe I can learn something.

[Q-Man]

Hello Rockets,

I thought I recognized you from the Klipsch Forum. I too sought out this site to see what these Altec guys would have to say, and what they might be able to help me with.

I've been trying different horns, drivers, and networks for over a year now. I like the 290s and 311 best of all so far. Although Just changing ouy the Klipsch K-400 horn to the University Cobreflex horn is the biggest bang for your buck.

When I A/B these different horns and drivers to a stock Klipschorn I find that the Klipsch midrange sounds as though there is a pillow stuffed in the horn. The biggest change is the horn, then comes the driver and the network in that order. I never understood what people ment bt a horn ringing untill I started comparing horns. Now, I can here the ringing of the K-400 horn. This Altec mod is much cleaner sounding and isn't as harsh. Some voices and instruments sound more natural. Another friend of mine from N.Y. who plays in a band for a living came to visit me about six months ago. He brought a few of his groups CDs.
I brought him into the room where I A/B these mods and changes. He was very impressed with the sound of the 290/311/2404H compared to the other midrange and tweeter combinations. I have it set up where I can switch back and forth between speakers with a flip of a switch. He said things like, "That's what my voice sounds like when we play live." "That's my guitar, I never heard it sound so real coming from a CD before."

I find that my three 290-16Ks have 1 to 2 dB more output at 400 Hz the my three 290-16Ls. This is why I did some diaphragm changing, but it didn't make any difference. So I plan on using the "K"s for the mains and front center. The "L"s for the rear surrounds and rear center. The 290s efficiency seems to be the same as the Klipsch K-55 driver so no attenuation is needed in the network. The JBL 2404H on the other hand needs to have a little.

I prefer the sound of a fully horn loaded bass horn, that's why I settled for the Klipschorn. I built the University Classic bass horn to see what it sound like. The Classic is very very nice. It is cleaner sounding then the Klipschorn, but drops off fast at 60Hz. Sometimes I think that I should use it instead of the Klipschorn, but the Klipschorn is strong down to 35 Hz so I can keep the subwoofer set to around 40 Hz. I also built the Jensen Imperial back loaded bass horn to see what it sounded like. Someone once told me that it was better sounding then the Klipschorn, so I had to give it a try. When you A/B them most people will pick the Imperial because it has outrageous bass output. It is about 6 dB louder then the Klipschorn from 50 to 25 Hz. This speaker is actually peaking from 50 down. The bass from this thing will pound you. My kids love it, I have a hard time telling them that this isn't a flat response and that it's not natural. Right now I'm usimg them for one of my pairs of rear surrounds. They are good for those action movies and all the rear explosions.

Sorry, I'm getting off of the topic.

Here is what my fried wrote me about the 290-16L driver that I shipped him. "Impedance plot of the raw driver shows the Fs is high (670Hz)." "That's a disapointment." Response to 400Hz will be a challenge since its below Fs." "Diaphragm operates in the supension dominated range (12dB/oct minimum rolloff). "Forget 300Hz." "Overall I'm depressed looking at this plot." "I thought that the Fs would be closer to 250-300Hz since the litature quotes useful response to those frequencies." "Below Fs, the response will not be very good." "Horn loading will help but distortion is significant."
"I measure impedance at about 3V, very low." " Even at that low of an output I can hear the difference between the driver operating below about 800Hz versus above." " The output gets a bit harsh below 800Hz." " Completely normal for a compression drive operating near Fz." " Also the Spl goes way up too." "No dought it sounds better then the K-55 driver, but operating at or below Fs is problematic and is one of the big reasons that the K-55 sounds bad." " The partial fix is to just selectively attenuate at that frequency using a notch filter between the driver and the autoformer." " Send me the 311-90 horn, because it will change the impeadance curve". "For hifi you don't want to be near Fs, but for PA it's ok so Altec can quote 300Hz."

So this is where I'm at right now.

I'll add more later.

Q.

[Rockets]

Bummer Q. This leaves me in a quandry as well.

I was hoping John's measurements would have been more favorable. I just ordered a set of horns, that 'supposedly' are similar to the Community BRH 90 Horns. I have to get an adapter for them as they are 1" throats. The reason I got them was I'd read you could take them down to 300hz, and their size would allow me to stay within the confines of a modified LS bass bin. Initially I was going to try them w/ the stock K-55, and later upgrade to the 290's. The K-55 should go down to 300hz http://www.atlassound.com/techLib/SLSheets/SL2.1551.PDF
Though now I'm concerned about the sound quality.

Having read your post/Johns report, I'm starting to wonder if I wouldn't be better off with plan "B". Forget the midrange horn, go with the 2123J, and use the 2404h tweeter. Doing so would save me a lot of hassles! I mean, most of the homework on this has already been done. I just need to beg for the crossover schematic from John! LOL!

Good luck, and BTW, I think this board may find Johns measurements of interest.

[Q-Man]

Rocktets,

Hang in there for a few days. John is working his magic as we speak. I'm hopeful that he can flatten out the frequency response a little more.
For me there is no going back now. I like what I hear and I have a lot invested in this mod. Since the 2404H tweeter can be crossed over to at 4500Hz instead of the 6000Hz required for the Klipsch K-77 tweeter may help. I believe this will make it a little easier to push the 290 lower. I tried adding another 3uF capacitor to the network to lower the crossover point another 100Hz. This gave me 1dB more output at 400Hz, but did nothing at 300Hz. This is when John & I decided to let him take over.

To tell you the truth if I wasn't so far into this I would just copy his JBL midrange mod. I wish we lived closer together so I could hear it. He will be able to compare the two once he plays with mine more. I'm interested in what he will have to say once he does that.

I looked into those Atlas drivers a while back, they are a lot like the K-55. I believe the K-55 was made by Atlas.